If President Bush's promise of massive humanitarian aid for the Iraqis is to materialize, the port of Umm Qasr in southern Iraq must be opened for safe travel.

And if the harbor, which was mined by the Iraqis to hamper a U.S. invasion, is opened, it will be due in no small measure to a pair of bottle-nosed Atlantic dolphins.

"We have some specially trained dolphins that are out there helping us to determine where mines may be in the channels," said Maj. Gen. Victor Renuart of the Central Command Tuesday.

Until the marine mammals arrived, clearing the mines was the job of the British. They located the mines by hand, and many said swimming in the port was like crawling around in mud with your eyes shut.

The mine-sniffing dolphins, part of the U.S. military's Mammal Maritime Unit, were flown into Umm Qasr by U.S. Navy helicopters Tuesday night. The dolphins, named Makai and Tacoma, began searching for mines on Wednesday.

Though the Navy has been training dolphins for years, this is their first operational deployment. With their natural sonar systems, the dolphins can detect mines even under the most difficult conditions.

They have been specially taught to avoid touching the mines, which might cause them to explode, said Capt. Mike Tillotson, a Navy bomb disposal expert. He said there was little risk to animals in doing this kind of work.

The biggest hazard could come from other indigenous dolphins in the waters of Umm Qasr.

Dolphins are territorial and there is a fear that local dolphins might drive the interlopers out, causing them to go AWOL.

The Navy started using marine mammals in the early 1960s, when military researchers noticed how sea mammals' highly developed senses, such as the dolphins' sonar, could be harnessed to locate mines and do other underwater tasks.

Dolphins were used in the 1970s during the Vietnam War. In the late 1980s, six Navy dolphins patrolled the Bahrain harbor to protect U.S. ships from enemy swimmers and mines. They also were used to escort Kuwaiti oil tankers through potentially dangerous waters.